• Journal of Electrochemical Science and Technology
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• 제1권2호
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• pp.69-74
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• 2010

Methodologies to improve photovoltaic performance of dye-sensitized solar cell (DSSC) are reviewed. DSSC is usually composed of a dye-adsorbed $TiO_2$ photoanode, a tri-iodide/iodide redox electrolyte and a Pt counter electrode. Among the photovoltaic parameters of short-circuit photocurrent density, open-circuit voltage and fill factor, short-circuit photocurrent density is the collective measure of light harvesting, charge separation and charge collection efficiencies. Internal quantum efficiency is known to reach almost 100%, which indicates that charge separation occurs without loss by recombination. Thus, light harvesting efficiency plays an important role in improvement of photocurrent. In this paper, technologies to improve light harvesting efficiency, including surface area improvement by nano-dispersion, size-dependent light scattering efficiency, bi-functional nano material, panchromatic absorption by selective positioning of three different dyes and transparent conductive oxide (TCO)-less DSSC, are introduced.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.752-754
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• 2009

High efficiency white organic light emitting diodes were fabricated by using an alignment free mask patterning method. Only red/green emission without any blue emission was observed in the red/green patterned region and blue emission was emitted in other area. A combination of the red/green and blue emission gave a high efficiency white emission. A maximum current efficiency of 30.7 cd/A and a current efficiency of 25.9 cd/A at 1000 cd/$m^2$ were obtained with a color coordinate of (0.38, 0.45).

• 전기학회논문지
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• 제64권5호
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• pp.732-738
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• 2015

In ac discharge, emission efficiency shows an time-varying characteristics during discharge. The phenomenon is caused by the potential distribution changes during the discharge, which indicates that a specific potential distribution can contribute to a high improvement of the emission efficiency. To create an artificial environment for a potential distribution favorable to emission efficiency, we used the asymmetric electrode structure and proved the capability. Our results showed that the ratio of the area of anode to cathode became larger, the emission efficacy was greatly improved.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권3호
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• pp.1599-1610
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• 2019

Intelligent services have expanded as Internet of Things (IoT) technology has evolved and new requirements emerge to accommodate various services. One new requirement is transmitting data over long distances with low-power. Researchers have developed low power wide area (LPWA) network technology to satisfy the requirement; this can improve IoT network infrastructure and increase the range of services. However, network coverage expansion causes several problems. The traffic load is concentrated at a specific gateway, which causes network congestion and leads to decreased transmission efficiency. Therefore, the approach proposed in this paper attempts to recognize and then avoid congestion through gateway channel hopping. The LPWA network employs multiple channels, so wireless channel hopping is available in a gateway. Devices that are not delay sensitive wait for the gateway to reappear on their wireless channel; delay sensitive devices change the wireless channel along the hopping gateway. Thus, the traffic load and congestion in each wireless channel can be reduced improving transmission efficiency. The proposed approach's performance is evaluated by computer simulation and verified in terms of transmission efficiency.

• 신재생에너지
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• 제3권3호
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• pp.14-19
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• 2007

A flow channel model of a bipolar plate with varying cross-sectional area was newly designed for improving performance and efficiency of a PEM fuel cell stack. As a result, the varying cross-sectional area model showed poor uniformity in velocity distribution, however, maximum velocity in the flow path is about 30% faster than that of the uniform cross-sectional area model. The proposed varying cross-sectional area model is expected to diffuse operating fluids more easily into diffusion layer because it has relatively higher values in pressure distribution compared with other flow channel models. It is expected that the implementation of the varying cross-sectional area model can reduce not only the mass transport loss but also the activation loss in a PEM fuel cell, and open circuit voltage of a fuel cell can thus be increased slightly.

• 한국습지학회지
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• 제13권3호
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• pp.603-611
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• 2011

갈대 지상경 삽목 효율성 제고를 위해 지상경 채취 지역, 매질, 식재 방법 그리고 지면으로부터의 거리에 따른 부위별 삽목 갈대 구분 등 다양한 방법들을 적용한 삽목 실험을 수행하였다. 그와 더불어 더 나은 삽목법을 다양한 환경의 여러 가지 갈대 생태형에 적용하여 보았다. 연구 결과 생태형, 채취 지역, 매질 등의 차이는 지상경에서의 새로운 경엽부 출현과 생육에 미미한 영향을 미친 반면 식재 방법과 갈대 지상경 중 삽목 부위 차이는 삽목 효율에 상대적으로 많은 영향을 미치는 것으로 확인되었다. 본 연구는 갈대의 지상경 삽목 시 삽목에 필요한 지상경 채취에 앞서 삽목을 통해 증식시킨 갈대를 도입시킬 습지의 환경적, 생태적 특성을 먼저 고려하여 채취 장소를 선정해야 함을 제안한다. 뿐만 아니라 위도나 고도에 따른 기후 조건 등을 고려한 갈대의 연중 생육특성도 함께 파악하여 적절한 시기에 지상경을 채취하고 채취한 갈대의 중간 정도 부위를 선택적으로 삽목에 활용하는 것을 제안한다. 그와 더불어 습지에서 갈대를 채취할 경우 활발한 확장이 이뤄지고 있는 확장부에서 삽목을 위한 지상경을 채취하는 것이 나으며 삽목을 위한 매질의 경우 상토보다는 통기성이 좋은 모래가 효율적이었다. 삽목 식재 방법의 경우 갈대 지상경이 지면에 수평 방향이 되도록 식재하게 되는 수평법이 지면에 수직으로 식재하는 수직법에 비해 훨씬 높은 효율을 나타내는 것으로 확인되었다. 지상경 삽목 효율 제고를 위해선 위 조건들뿐만 아니라 진딧물과 같은 병해충들로부터 갈대 삽목체가 피해 받지 않도록 하는 차원에서의 관리 방안 또한 함께 고려되어야 할 것이다.

• 한국실내디자인학회:학술대회논문집
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• 한국실내디자인학회 2008년도 춘계학술발표대회 논문집
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• pp.50-53
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• 2008

Recently as the efficiency of meal area in the neighborhood facilities has decreased, the user is not satisfied about the existing meal area quality. There are problems due to crucial administration due to ineffective use of the meal area and the in-charge. So, a new meal system is coming up with one meal form at one place with time wise classification to satisfy the users and owner. In this plan, the meal area at basement 1 of Korea Advertisement Culture Hall is not just the existing meal area but in day it is a restaurant, at night a vacant hall and in the weekend it is a banquet hall. Such a premium meal area designed by developing the meal area that has different usage as per time slot is named as "M-KITCHEN" and we intend to plan in such a way. The complete "M-KITCHEN"consists largely of entrance/ exit, food distribution area, eating area, specialized restaurant, rest area, kitchen, warehouse etc. This area consists again of multimedia street entrance "M-street", food distribution area "M-kitchen", meal area "M-place", "M-plaza", "Wall pond", "Layer deck", specialized restaurant "M-china", "M-shushi", rest area "Gardening".

• Journal of Biosystems Engineering
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• 제2권1호
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• pp.49-54
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• 1977

In order to obtain the field efficiency of the power tiller plowing on the various size of and its length-width field tests were performed with 8ps.10ps. power tiller popularly used in the korean rural area, and Satoh 5ps. made in Japan, Land Master 5ps. made in England were tested to compare with the field efficiency of the above power tillers. The results obtained in this tests were as follows ; 1. In considering of the resting time and the refueling time and others, the field efficiency of Satoh was the highest among the power tillers as to be 80%, at the 8ps. power tiller 76.5%, at the 10ps. power tiller 79.3% and the lowest field efficiency was obtained at the Land Master as 75.7%. 2. The field efficiency of the each power tiller increased as the ratio of the length to width of the field was increased. 3. The increasing rate of field efficiency was much bigger in the below the ratio of 5 : 1 but at the upper ratio increased above, the ratio was nearly constant. 4. The field efficiency of the power tiller was higher at the smaller power tiller than the larger, except the Land Master , because of easily operating and turning of the power tiller by virtue of its lighter weight.

• 무역학회지
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• 제47권4호
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• pp.271-292
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• 2022

In Korea, the road transport industry is pointed out as a major cause of air pollutants, so management control is needed. Existing studies used only positive input and output variables to measure regional efficiency. However, it is necessary to consider the environmental pollution problem in efficiency analysis. In this study, an undesirable SBM analysis using CO₂ was conducted to measure efficiency of domestic regions. In addition, SDM was conducted to examine the ripple effect between domestic regions. As a result of the analysis, the efficiency of the capital area such as Seoul, Gyeonggi, and Incheon was high in the road transport industry. However, the efficiency of the road transportation industry in Daegu and Gangwon was low. In the SDM analysis, it was found that the regional equipment capabilities had a great influence on efficiency. In order to improve efficiency, it is necessary to increase and improve the equipment capacity of the road transport industry.

• International Journal of Internet, Broadcasting and Communication
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• 제16권1호
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• pp.287-296
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• 2024

Artificial intelligence (AI), the Internet of Things (IoT), and Big Data are playing important roles in improving or upgrading energy efficiency. Furthermore, their roles in energy efficiency are expected to become more and more essential. This study conducted a bibliometric comparative analysis on the features in the articles on the AI, the IoT, and the Big Data in energy efficiency by using the Web of Science database and compared the features in their trends in article publications, citations, countries, research areas, journals, and funding agencies from 2012 to 2022. This study attempted to make significant contributions by shedding new light on the following features. Among the AI, the IoT, and the Big Data in energy efficiency, the most articles were published and the most article citations were received in the AI in energy efficiency. China was found out to be the most leading country. Engineering and computer science were revealed to be the first research area. IEEE Access and IEEE Internet of Things were ranked with first journal. National Natural Science Foundation of China was the first research funding agency concerning the articles published in the AI, the IoT, and the Big Data in energy efficiency from 2012 to 2022.