• Journal of the Institute of Electronics Engineers of Korea CI
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• v.45 no.6
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• pp.94-105
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• 2008

Numerous platforms have been developed for ZigBee-based network embedded systems. Also, operating systems like TinyOS have been installed to facilitate efficient implementation of wireless sensor network applications which collect data, and/or execute commands. First of all, porting an operating system on a new platform may need invention of a substitute for a required but unsupported hardware component. This paper presents a multiplexed virtual system timer for a platform without a counter comparator which we have contrived to emulate by using an extra counter. Such porting also injects unexpected faults which cause a variety of painful failures. Unfortunately, TinyOS requires to handle a lot of asynchronous hardware interrupts which are hard to trace during debugging. Besides, simulators are not available for a new platform since the models of hardware on the platform are not usually developed, yet. We propose novel instrumentation techniques which can be used to effectively trace the bugs in such lack of debugging environment. These techniques are used to identify and fix a great deal of nasty issues in porting TinyOS 2.0 on MG2400 and MG2455 platforms made by RadioPulse Inc.

• Journal of Korean Society of Forest Science
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• v.98 no.6
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• pp.633-638
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• 2009

This study was conducted to develop stem taper equations and stem volume tables for Eucalyptus pellita and Acacia mangium plantations in Kalimantan, Indonesia. To derive a most adequate taper equation for the plantations, three models - Max & Burkhart, Kozak, and Lee models - were applied and their fitness were statistically analyzed by using fitness index, bias, and standard error of bias. The result showed that there is no significant difference between the three models, but the fitness index was slightly higher in the Kozak model. Therefore, the Kozak model was chosen for generating stem taper equations and stem volume tables for the Eucalyptus pellita and Acacia mangium plantations. The resulted stem volume table was compared to the local volume table used in Kalimantan regions, but no significant difference was found in the stem volume estimation. It is expected that the results of this study would provide a good information about the tree growth in abroad plantations and support a reliable decision-making for their management.

• Journal of the Korean Geographical Society
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• v.40 no.6 s.111
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• pp.770-788
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• 2005

In this article, major research trends are examined mainly from articles published in Journal of the Korean Geography, academic society journals of sub-fields in geography and Ph.D. dissertations in geography of universities in Korea. Based on the research trends up to current point, issues and research directions in order to raise the status of Korean Geography in the twenty first century are prospected. Sixty years of Korean Geography can be divided into 4 periods such as before 1970s, during the 1980s, during the 1990s, and the period after the 2001. Each period of time revealed distinct aspects of development both quantitatively and qualitatively. For the last 60 years, the study of Korean Geography has gone through enormous changes in the number of articles with dynamics and variety in contents and methodology, breathing with the changes of the Korean society. Experiencing urbanization and industrialization along with rapid economical growth, the study of Korean Geography has progressed by analyzing the issues and problems of national space and conducting various researches from the case studies for problem-solving to the theoretical and policy oriented studies. The key-words such as 'knowledge based information society', 'aged society', and 'the era of globalization' will be realized in the twenty flit century. And environment-friendly policies for sustainable development will be more stressed in a globalized world. In order to provide research methods and alternatives suitable for newly transformed global society and for utilizing the essence of Geography in the future, the studies on Korean Geography should actively focus on integrative studies between physical and human geography, on interdisciplinary studies, on regional studies related to foreign countries and North Korea, and on the establishment of Korean geographical theory and model.

• Journal of Broadcast Engineering
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• v.25 no.4
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• pp.560-568
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• 2020

In recent years, as network technology develops, the usage of streaming services by users is increasing. However, the complexity of streaming services is also increasing due to various terminal environments. Even when streaming the same content, it is necessary to re-encode the content according to the type of service. In order to solve the complexity and latency of the streaming service, Moving Picture Experts Group (MPEG) has standardized the Common Media Application Format (CMAF). In addition, as content transmission using a communication network becomes possible, the Republic of Korea's Ultra High Definition (UHD) broadcasting standard has been enacted as a hybrid standard using a broadcasting network and a communication network. The hybrid service enables various services such as transmitting additional information of contents or providing user-customized contents through a communication network. The Republic of Korea's UHD transmission standard utilizes MPEG Media Transport (MMT), and Mobile MMT is an extension of MMT to provide mobile network-specific functions. This paper proposes a method of inserting CMAF contents suitable for various streaming services using signaling messages of MMT and Mobile MMT. In addition, this paper proposes a model for content insertion system in heterogeneous network environment using broadcasting and communication networks, and verifies the validity of the proposed technology by checking the result of content insertion.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.3
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• pp.551-564
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• 2016

Earthworks are the fundamental steps in a construction job, and are mainly comprised of smaller tasks performed by construction machinery. The productivity of the construction job can be improved by optimizing excavation, filling, and other such operations. Earthworks involve a lot of mechanical work performed by the collaboration between various kinds of construction equipment, which in turn leads to higher fuel consumption. Actual earthworks depend mostly on the intuition and experience of the driver of the machines, thus leading to inefficiency and environmental problems caused by unnecessary emission of carbon, Recently automated and information-oriented technologies are consistently being researched towards the improvement of efficiency of earthworks in the construction industry. The present research involves the introduction and understanding of the decision-making elements of heuristics which can be applied to the earthwork planning. A method is also suggested for creating an effective work path for construction machine to perform task packages (TP) for cutting and filling processes. A simulation test is performed to verify the effectiveness of suggested methods in terms of space interference and total moving distance of construction equipment.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.3
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• pp.1173-1180
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• 2013

The construction industry has been a major player in Korean economy growth and it has been accountable for more than 15% of GDP during the last decade. However, fast-growing construction industry has also produced some unpleasant side-effects. Environmental problems are identified one of the main issues in the Korean construction industry and they are closely related to minimizing the carbon emission and delivering environmental-friendly green products. The movement of green construction, now, is considered the next driving force for the industry which has significant impacts on the future. This research investigates this green construction while focusing on governmental policy implications such as green certificate for construction products. Green building has long been recognized as the leading green construction product and the green trends have expanded to infrastructure construction such as road construction. Therefore, this research concentrates on various green road certification processes in the United States in order to develop a framework for Korean green road certification. In doing so, some of the green roads application has also been analyzed. This research intends to provide background information for Korean green construction policies, especially on green road certification.

• Information Systems Review
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• v.16 no.3
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• pp.25-47
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• 2014

IT project is a knowledge-based project with high uncertainty in role assignment and task allocationamong team members. This study empirically investigate steam members' interactive behavior in IT projects based on the framework of social interdependence theory. The goal and task interdependencebetween team members were posited as antecedents of project performance with communication effectiveness and knowledge sharing as mediating variables. To test the research model, a dataset was collected form IT and business professional pairs of 123 IT project teams. The results indicated that the theory of social interdependence is applicable to explaining the promotive interaction in IT project teams. In detail, task interdependence appears to have influence on both promotive interactions (communication effectiveness and knowledge sharing), and goal interdependence influences only on communication effectiveness. Knowledge sharing is found to be a significant mediator between social interdependence and project performance. However, communication effectiveness only indirectly influences project performance via knowledge sharing. Academic and practical implications are discussed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.10
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• pp.817-822
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• 2017

The braking system is one of the most important components in vehicles and machines. It must exert a reliable braking force when they are brought to a halt. Generally, frictional heat is generated by converting kinetic energy into heat energy through friction. As the kinetic energy is converted into heat energy, high temperature heat is generated which affects the mechanical behavior of the braking system. Frictional heat affects the thermal expansion and friction coefficient of the brake system. If the temperature is not controlled, the brake performance will be decreased. Therefore, it is important to predict and control the heat generation of the brake. Various numerical analysis studies have been carried out to predict the frictional heat, but they assumed the existence of boundary conditions in the numerical analysis to simulate the frictional heat, because the simulation of frictional heat is difficult and time consuming. The results were based on the assumption that the frictional heat is different from the actual temperature distribution in a rotating brake system. Therefore, the reliability of the cooling effect or thermal stress using the results of these studies is insufficient. In order to overcome these limitations and establish a simulation procedure to predict the frictional heat, this study directly simulates the frictional heat generation by using a thermal-structure coupling element. In this study, we analyzed the thermo-mechanical behavior of a brake model, in order to investigate the thermal characteristics of brake systems by using the Finite Element method (FEM). This study suggests the necessity to directly simulate the frictional heating and it is hoped that it can provide the necessary information for simulations.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.3
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• pp.219-229
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• 2018

This paper proposes Kalman Filter-based relative navigation algorithms for proximity tasks such as rendezvous/docking/cluster-operation of spacecraft using PSD Sensors and Infrared Beacon Modules. Numerical simulations are performed for comparative analysis of the performance of each relative-navigation technique. Based on the operation principle and optical modeling of the PSD Sensor and the Infrared Beacon Module used in the relative navigation algorithm, a measurement model for the Kalman filter is constructed. The Extended Kalman Filter(EKF) and the Unscented Kalman Filter(UKF) are used as probabilistic relative navigation based on measurement fusion to utilize kinematics and dynamics information on translational and rotation motions of satellites. Relative position and relative attitude estimation performance of two filters is compared. Especially, through the simulation of various scenarios, performance changes are also investigated depending on the number of PSD Sensors and IR Beacons in target and chaser satellites.

• Journal of Broadcast Engineering
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• v.17 no.4
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• pp.584-595
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• 2012

Recently, 3D stereoscopic video and HTTP adaptive streaming technologies have received a lot of attention from relevant industrial fields and markets in terms of multimedia contents and delivery services, respectively. It is expected that promising and marketable service models can be created by means of these noticeable two technologies. However, current standard specifications do not provide a method for organized connection between those two technologies. 3D stereoscopic video services are weighted in broadcasting and storage services that are only available under environments in which the network bandwidth is guaranteed or free. Also, HTTP adaptive streaming technologies only provide plain 3D service methods that are dependent on particular Codec. Therefore, this paper proposes 3D video delivery format for HTTP adaptive streaming service which enables stable and seamless display for various stereoscopic video sequences over internet networks. The proposed technology is designed on the basis of Stereoscopic Video Application Format which is a service-oriented standard specification for storing stereoscopic video sequences. Also, this delivery format is directly applicable over DASH that is the representative standard technology for HTTP adaptive streaming services. The delivery format proposed in this paper has been submitted to MPEG and it has been accepted as a working draft, thus it expected to pave the way for practical industrialization in relevant fields from now on.