• Journal of KIISE
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• v.42 no.12
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• pp.1495-1502
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• 2015

Data compression involves a trade-off between delay time and data size. Greater delay times require smaller data sizes and vice versa. There have been many studies performed in the field of wireless sensor networks on increasing network life cycle durations by reducing data size to minimize energy consumption; however, reductions in data size result in increases of delay time due to the added processing time required for data compression. Meanwhile, as energy generation occurs periodically in solar energy-based wireless sensor networks, redundant energy is often generated in amounts sufficient to run a node. In this study, this excess energy is used to reduce the delay time between nodes in a sensor network consisting of solar energy-based nodes. The energy threshold value is determined by a formula based on the residual energy and charging speed. Nodes with residual energy below the threshold transfer data compressed to reduce energy consumption, and nodes with residual energy above the threshold transfer data without compression to reduce the delay time between nodes. Simulation based performance verifications show that the technique proposed in this study exhibits optimal performance in terms of both energy and delay time compared with traditional methods.

• Journal of Environmental Science International
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• v.24 no.8
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• pp.1003-1013
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• 2015

The Ministry of Trade, Industry and Energy is now placing emphasis on the importance of a new and renewable energy resource map service as an essential means of promoting the dissemination and adoption of renewable energy and other related industrial activities. To raise satisfaction with the new and renewable energy resource map service and promote its utilization, a survey was conducted on a sample group with an academic research background, i.e. employees of the Korea Institute of Energy Research (KIER) who have a thorough understanding of the technological concepts behind the new and renewable energy resource map. Statistical analysis of the survey results showed a high level of overall satisfaction with the web service for the new and renewable energy resource map. Therefore, it was concluded that the development of practical contents rather than the enhancement of web service convenience is required. A statistically significant trend was also observed whereby, the longer the professional career of the survey respondents, the greater their perception and utilization of, and satisfaction with, the enhanced service, which indicates that their level of understanding and utilization of technological concepts corresponds to their research experience record. In addition, the results obtained from the questionnaires regarding the evaluation of the utilization value of the resource map service indicated that use of the service was equally high in terms of political, business and academic applications. The results confirmed the need to develop multidimensional resource map contents that can be applied to as many fields as possible, rather than focusing on a specific terrain.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.4 no.1
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• pp.5-24
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• 2010

Data fusion is an attractive technology because it allows various trade-offs related to performance metrics, e.g., energy, latency, accuracy, fault-tolerance and security in wireless sensor networks (WSNs). Under a complicated environment, each sensor node must be equipped with more than one type of sensor module to monitor multi-targets, so that the complexity for the fusion process is increased due to the existence of various physical attributes. In this paper, we first investigate the process and performance of multi-attribute fusion in data gathering of WSNs, and then propose a self-adaptive threshold method to balance the different change rates of each attributive data. Furthermore, we present a method to measure the energy-conservation efficiency of multi-attribute fusion. Based on our proposed methods, we design a novel energy equilibrium routing method for WSNs, viz., multi-attribute fusion tree (MAFT). Simulation results demonstrate that MAFT achieves very good performance in terms of the network lifetime.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.67
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• pp.143-162
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• 2015

Russia has a huge amount of energy resources. It is an attractive factor to countries which spend loads of energy. Republic of Korea is also one of large energy consumption countries. Therefore, It will be needed to raise energy cooperation with Russia. It's companies will increase trade focusing on the energy industry in the long term. Recently, However, Foreign companies should be careful when they enter the rapidly changing Russia market. In other words, companies will need a strategic approach to prepare the early case assessment and how to solve a possible dispute as they analyze cost and profit in business. This study is analyzing several dispute cases related in Russia. It presents some strategies for Korean companies such as dispute resolution method, arbitration institution selection method and so on. In addition, it proposes the introduction of the early case assessment for reducing a waste of time and cost. Furthermore, according as the importance of OECD Guidelines for Multinational Enterprises is highlighted in international community, companies should prepare practical division to establish a system of responsible business conduct. Finally, they will have to get an advice and counseling from the Russia legal experts in the early stages of the contract.

• Journal of Communications and Networks
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• v.10 no.2
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• pp.213-220
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• 2008

This paper analyzes a broadcasting technique for wireless multi-hop sensor networks that uses a form of cooperative diversity called opportunistic large arrays (OLAs). We propose a method for autonomous scheduling of the nodes, which limits the nodes that relay and saves as much as 32% of the transmit energy compared to other broadcast approaches, without requiring global positioning system (GPS), individual node addressing, or inter-node interaction. This energy-saving is a result of cross-layer interaction, in the sense that the medium access control (MAC) and routing functions are partially executed in the physical (PHY) layer. Our proposed method is called OLA with a transmission threshold (OLA-T), where a node compares its received power to a threshold to decide if it should forward. We also investigate OLA with variable threshold (OLA-VT), which optimizes the thresholds as a function of level. OLA-T and OLA-VT are compared with OLA broadcasting without a transmission threshold, each in their minimum energy configuration, using an analytical method under the orthogonal and continuum assumptions. The trade-off between the number of OLA levels (or hops) required to achieve successful network broadcast and transmission energy saved is investigated. The results based on the analytical assumptions are confirmed with Monte Carlo simulations.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.2
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• pp.230-238
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• 2015

The main purpose of this paper is to suggest opportunities for reducing $CO_2$ emission in energy conversion of a vehicle, focused on auxiliary energy improvement in the automotive field. As part of worldwide efforts to curb global warming and to protect the domestic industry as trade barriers, many countries have set goals to regulate greenhouse gas emissions. As an example, new $CO_2$ emission regulation in EU was expected to go into effect strictly in 2020. Therefore, global car-makers need to establish strategic responsiveness of the regulations. This paper shows $CO_2$ economic value by using the correct interpretation of the relevant laws and regulations. The $CO_2$ value analyzed using quantitative figures leads to the possibility of auxiliary(accessories, HVAC, electric apparatus etc.) technology for improving fuel economy. As a result, this study generalizes the meaning of electric power saving for each driving mode by auxiliary energy improvement.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.5
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• pp.525-530
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• 2023

Stretchable piezoelectric energy harvester (S-PEHs) based on composite materials are considered one of the potential candidates for realizing wearable self-powered devices for smart clothing and electronic skin. However, low energy conversion performance and expensive stretchable electrodes are major bottlenecks hindering the development and application of S-PEHs. Here, we fabricated the S-PEH by adopting the piezoelectric composites with enhanced stress transfer properties and kirigami-patterned textile electrodes. The optimum contents of piezoelectric BaTiO₃ nanoparticles inside the carbon nanotube/ecoflex composite were selected as 30 wt% considering the trade-off between stretchability and energy harvesting performance of the device. The final S-PEH shows an output voltage and mechanical stability of ~5 V and ~3,000 cycles under repeated 150% of tensile strain, respectively. This work presents a cost-effective and scalable way to fabricate stretchable piezoelectric devices for self-powered wearable electronic systems.

• Journal of Semiconductor Engineering
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• v.1 no.1
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• pp.13-30
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• 2020

Radio frequency (RF) energy harvesting technology have become a reliable and promising alternative to extend the lifetime of power-constrained wireless networks by eliminating the need for batteries. This emerging technology enables the low-power wireless devices to be self-sustaining and eco-friendly by scavenging RF energy from ambient environment or dedicated energy sources. These attributes make RF energy harvesting technology feasible and attractive to an extended range of applications. However, despite being the most reliable energy harvesting technology, there are several challenges (especially power conversion efficiency, output DC voltage and sensitivity) poised for the implementation of RF energy harvesting systems. In this article, a detailed literature on RF energy harvesting technology has been surveyed to provide guidance for RF energy harvesters design. Since signal strength of the received RF power is limited and weak, high efficiency state-of-the-art RF energy harvesters are required to design for providing sufficient DC supply voltage to wireless networks. Therefore, various designs and their trade-offs with comprehensive analysis for RF energy harvesters have been discussed. This paper can serve as a good reference for the researchers to catch new research topics in the field of RF energy harvesting.

• Journal of Energy Engineering
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• v.20 no.1
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• pp.63-76
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• 2011

This paper studies the impact of Korean introduction of the Generalized System of Preferences(GSP) to developing countries, which are continuously arguing to support research and development for reducing greenhouse gas(GHG) emission with developed countries in the Conference of the Parties(COP) of UNFCCC. This paper is focusing on the expecting effects of trade and GHG emission reduction when Korea provides GSP to Indonesia, Brazil, and Ethiopia, which are selected in the first session of Global Green Growth Institute(GGGI). This paper uses the methodology of the intra-industry trade index multiplied by Korean import-induced coefficients. To Indonesia, Korean probable GSP would benefit exports of Indonesian agriculture, forestry, fishery, and livestock farming industries, which would contribute to Indonesian reduction of GHG emission. To Brazil, the exports to Korea would increase in the GHG sensitive industries such as metal, fat, oils, food, and beverage industries. Ethiopia belongs to the least developed countries. So Korean GSP would support the exports and GHG reduction in Ethiopian agriculture, forestry, fisheries, textiles, and leather industries. Without conflicting most favored nation treatment(MFN) principle in WTO, the introduction of GSP would be a good compensation for GHG reduction to developing countries.

• Environmental and Resource Economics Review
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• v.24 no.2
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• pp.411-433
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• 2015

This paper decomposed energy productivity changes across 14 Korean manufacturing industries into 5 components, technological catch-up(EC), technological progress(TC), and changes in labor-energy ratio(LC), capital-energy ratio(KC) and energy mix(EMC). Then we also figured out the possible relationship between energy productivity change and export growth rate across the industries. It is found that (1) technological progress, changes in capital-energy ratio and energy mix contribute to energy productivity growth in Korea during the sample period, (2) technological progress is the primary driving forces for energy productivity growth, (3) increase in export growth rate had a positive impact on energy productivity growth excepting a part of energy-intensive industries.