• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.11
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• pp.2411-2417
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• 2012

Globally, the emergence of smart phones vitalized the ecosystem of mobile data service industry. Consequentially, mobile data traffic has been explosively growing and the speed of growth will be more steep. New spectrum will be required in order to properly accommodate the explosively growing mobile data traffic. However, it will be difficult to acquire a sufficient guard band between different frequency bands because the range of frequency which is suitable for wireless communications is limited. Thus, the performance degradation caused by inter-band interference will be one of challenging problems in the next generation mobile communication systems. In this paper, we analyze the performance degradation caused by inter-band interference by computer simulations in various environments. Our results show that the impact of the inter-band interference is more critical when own signal is poor or its own interference from neighboring cells is low.

• Journal of Engineering Education Research
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• v.14 no.3
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• pp.25-30
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• 2011

This paper is being established in Sungkyunkwan University based on a new lecture, "Scientific and Technical Writing and Presentation". The course feature and core educational goal is mainly to focus on challenging students to be able to learn scientific engineering communication, recognizing problem and solving it which involve a basic process of formulating thinking and expression skills. Basically, Scientific and Technical Writing and Presentation lecture is a blended learning that will put students in various type of problem based learning (PBL) in order to distinctively build their problem solving skills and emphasizing self-leadership skills in their profession. Through group activity participants in this learning area will be exposed to more specific problems to ensure more individual participation and in the same time they will be able to actively review the objective of their own activity which are part of this course objectives.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.11
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• pp.3876-3895
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• 2014

Recently, Heterogeneous Network (HetNet) with Coordinated Multi-Point (CoMP) scheme is introduced into Long Term Evolution-Advanced (LTE-A) systems to improve digital services for User Equipments (UEs), especially for cell-edge UEs. However, Radio Resource Management (RRM), including Resource Block (RB) scheduling and Power Allocation (PA), in this scenario becomes challenging, due to the intercell cooperation. In this paper, we investigate the RRM problem for downlink transmission of HetNet system with Joint Processing (JP) CoMP (both joint transmission and dynamic cell selection schemes), aiming at maximizing weighted sum data rate under the constraints of both transmission power and backhaul capacity. First, joint RB scheduling and PA problem is formulated as a constrained Mixed Integer Programming (MIP) which is NP-hard. To simplify the formulation problem, we decompose it into two problems of RB scheduling and PA. For RB scheduling, we propose an algorithm with less computational complexity to achieve a suboptimal solution. Then, according to the obtained scheduling results, we present an iterative Karush-Kuhn-Tucker (KKT) method to solve the PA problem. Extensive simulations are conducted to verify the effectiveness and efficiency of the proposed algorithms. Two kinds of JP CoMP schemes are compared with a non-CoMP greedy scheme (max capacity scheme). Simulation results prove that the CoMP schemes with the proposed RRM algorithms dramatically enhance data rate of cell-edge UEs, thereby improving UEs' fairness of data rate. Also, it is shown that the proposed PA algorithms can decrease power consumption of transmission antennas without loss of transmission performance.

• Journal of Food Hygiene and Safety
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• v.35 no.1
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• pp.1-5
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• 2020

Foodborne diseases (FBD) pose significant public health problems and economic losses worldwide. In recent years, emerging foodborne diseases have resulted mainly from novel bacteria, viruses, protozoa, mycotoxins, prions in animal and plant sources. The consumption of unsafe food contaminated with harmful bacteria, viruses, parasites or chemical agents or naturally occurring toxins results in high morbidity and mortality. However, estimating the incidence and burden of FBD is a huge global challenge due to the difficulty in food source attribution to specific pathogenic or chemical hazards, underreported cases, diagnosing how infections are transmitted or when a person is infected are not well understood and thus makes the control of FBD very challenging. Therefore, implementing comprehensive food safety strategies and policies, enhancing surveillance, ensuring resilient health system, and intensifying education and training to ensure safe food and prevent foodborne diseases is everybody's responsibility.

• Archives of Reconstructive Microsurgery
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• v.17 no.2
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• pp.68-74
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• 2008

Segmental defects of the tibia after open fractures, sepsis and a tumor surgery are among the most difficult and challenging clinical problems. Tibia defects in these situations are complicated with infection and are resistant to conventional bone grafting techniques. The aim of this study is to report the results and discuss the role of free flap followed by ipsilateral vascularized fibular transposition (IVFT) for reconstruction of tibia defects. Ten patients had free flap followed by IVFT in the period 1989~2007. Mean age was 25.3 years. The patients were followed for an average of 3.4 years. All flaps were survived including 1 case with venous thrombosis requiring additional surgery. The average time to union of proximal and distal end was 5.2 months, 8.2 months, each other. All transposed fibula were viable at last follow-up. IVFT offers the advantages of a vascularized graft. In patients with large bone and soft tissue defects combined with infection, free flap followed by IVFT is an useful and reliable method without microvascular anastomosis.

• Journal of Dental Anesthesia and Pain Medicine
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• v.17 no.3
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• pp.163-181
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• 2017

In the field of orofacial surgery, a red blood cell transfusion (RBCT) is occasionally required during double jaw and oral cancer surgery. However, the question remains whether the effect of RBCT during the perioperative period is beneficial or harmful. The answer to this question remains challenging. In the field of orofacial surgery, transfusion is performed for the purpose of oxygen transfer to hypoxic tissues and plasma volume expansion when there is bleeding. However, there are various risks, such as infectious complications (viral and bacterial), transfusion-related acute lung injury, ABO and non-ABO associated hemolytic transfusion reactions, febrile non-hemolytic transfusion reactions, transfusion associated graft-versus-host disease, transfusion associated circulatory overload, and hypersensitivity transfusion reaction including anaphylaxis and transfusion-related immune-modulation. Many studies and guidelines have suggested RBCT is considered when hemoglobin levels recorded are 7 g/dL for general patients and 8-9 g/dL for patients with cardiovascular disease or hemodynamically unstable patients. However, RBCT is occasionally an essential treatment during surgeries and it is often required in emergency cases. We need to comprehensively consider postoperative bleeding, different clinical situations, the level of intra- and postoperative patient monitoring, and various problems that may arise from a transfusion, in the perspective of patient safety. Since orofacial surgery has an especially high risk of bleeding due to the complex structures involved and the extensive vascular distribution, measures to prevent bleeding should be taken and the conditions for a transfusion should be optimized and appropriate in order to promote patient safety.

• International Journal of Railway
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• v.6 no.2
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• pp.33-44
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• 2013

In recent years, energy consumption in the transportation sector by expanding motorization continues to increase in almost every country in the world. Moreover, the growth rate of the transportation energy consumption is significantly higher than those of the civilian and industrial sectors. Therefore, every country strives to reduce its dependence on private transport, which is the main contributor to the transportation energy consumption. In many countries, concepts such as Transit Oriented Development (TOD) or New Urbanism, which controls road traffic by increasing the proportion of the public transportation significantly, have been implemented to encourage a modal shift to public transport. However, the level of change required for eliminating environmental problems is a challenging task. Minimizing transportation energy consumption by controlling the increase of the traffic demand and maintaining the level of urban mobility simultaneously is a pressing dilemma for each city. Grasping the impact of the diversity of the urban transport and infrastructure is very important to improve transportation energy efficiency. However, the potential for reducing urban transportation energy consumption has often been ineffectively demonstrated by the diversity of cities. Therefore, the accuracy of evaluating the current efficiency rate of the urban energy consumption is necessary. Nevertheless, quantitative analyses related to the efficiency of transportation energy consumption are scarce, and the research on the current condition of consumption efficiency based on international quantitative analysis is almost nonexistent. On the basis of this background problem definitions, this research first built a database of the transportation energy consumption of private modes in 119 cities, with an attempt to reflect individual travel behaviors calculated by Person Trip data. Subsequently, Data Envelopment Analysis (DEA) was used as an assessment method to evaluate the efficiency of transportation energy consumption by considering the diversity of the urban traffic features in the world cities. Finally, we clarified the current condition of consumption efficiency by attempting to propose a target values for improving transportation energy consumption.

• Computational Structural Engineering
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• v.9 no.3
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• pp.169-177
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• 1996

The focus of this study is on the problem of the design of structure of undetermined topology. This problem has been regarded as being the most challenging of structural optimization problems, because of the difficulty of allowing topology to change. Conventional approaches break down when element sizes approach to zero, due to stiffness matrix singularity. In this study, a novel nonlinear programming formulation of the topology problem is presented. Its main feature is the ability to account for topology variation through zero element sizes. Stiffness matrix singularity is avoided by embedding the equilibrium equations as equality constraints in the optimization problem. Although the formulation is general, two dimensional plane elasticity examples are presented. The design problem is to find minimum weight of a plane structure of fixed geometry but variable topology, subject to constraints on stress and displacement. Variables are thicknesses of finite elements, and are permitted to assume zero sizes. The examples demonstrate that the formulation is effective for finding at least a locally minimal weight.

• Korean System Dynamics Review
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• v.14 no.4
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• pp.113-141
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• 2013

The main purpose of this research is to introduce PsyCap(Positive Psychological Capital) and new leadership helping ordinary people to create positive thinking and leading to social integration in South Korea. Additionally, by looking at conventional leadership theories and by applying the PsyCap to leadership based on causal loop analysis, this study is to seek new approach which political leader is able to communicate with the people and can help the people to build positive mine. Throughout this study, there are several important implications how political leader can lead to social integration and stable political development in South Korea. In particular, when political leader encourage the people to have confidence to take on and put in the necessary effort to succeed at challenging tasks, when political leader make the people a positive attribution (optimism) about succeeding now and in the future, when political leader help the people to persevere toward goals and redirection paths to goals (hope) in order to succeed, and when political leader make the people beset by problems and adversity environment to overcome these concerns, it can be expected political leader to build social integration and the people to create positive thinking which has been emphasized by political leader in South Korea. Finally, 21st century has required new political leadership that the people are able to make positive psychological capital composed by optimism, hope, confidence, and resilience.

• Journal of Arbitration Studies
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• v.13 no.2
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• pp.181-209
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• 2004

This Study is divided into 5 separate Parts and an Abstract. Part Ⅰ, Ⅱ consist mostly of a collection of problems, current status, motives and the future of ADR. In Pert Ⅲ was described ADR as policies of judicial settlements. We must accept that a diversity of legal culture will always continue to exist. Accordingly we must learn to accommodate those differences of 'culture' around us and to harmonize conflicting laws. This recognition of our reality should in no way be confused with pessimism. In fact if one accepts this perspective of the world ,the study of law seems enriched and becomes academically more challenging. Recently, in the United States, interest in alternative settlement mechanism has increased greatly, which leads me to wonder why such a phenomenon has taken place. In the first place, I'm amazed at the extent to which conciliation or mediation-or the new word, I guess, is alternative dispute resolution, which by now has its own acronym, "A.D.R,"-have gained attention here recently. When 35 years ago, there was virtually no interest in conciliation in this country at the time. What interest there was, was no in the law schools. But looking at the situation now, we have a spate of publications on the subject; we have organizations that are established for no other reason than to promote alternative dispute settlement. We have courses in the law schools. The American Association of Law Schools and the American Bar Association also have active programs. So we have to ask ourselves why. The difference between now and 35 years are striking. On the other hand, I think the interest of the public in ADR has probably been greatly enhanced by the politics of the so-called "poverty programs." I think that many of these assistance programs for the poor-and I do think the "poor" have become a rather expansive political movement beyond simply taking care of the most marginal people of society-have generated money to explore this kind of dispute resolution.