• Journal of Electrochemical Science and Technology
• /
• v.2 no.3
• /
• pp.168-173
• /
• 2011

The availability, low toxicity, and high degree of technological development make silicon the most likely material to be used in solar cells, the cost of solar cells depends entirely on cost of high purity silicon production. The present work was conducted to electrodeposite of silicon from $K_2SiF_6$, an inexpensive raw material prepared from fluorosilicic acid ($H_2SiF_6$) produced in Iraqi Fertilizer plants, and using inexpensive graphite material as cathode electrode. The preparation of potassium fluorosilicate was performed at ($60^{\circ}C$) in a three necks flask provided with a stirrer, while the electro deposition was performed at $750^{\circ}C$ in a three-electrodes configuration with melt containing in graphite pot. High purity potassium fluorosilicate (99.25%) was obtained at temperature ($60^{\circ}C$), molar ratio-KCl/$H_2SiF_6$(1.4) and agitation (600 rpm). Spongy compact deposits were obtained for silicon with purity not less than (99.97%) at cathode potential (-0.8 V vs. Pt), $K_2SiF_6$ concentration (14% mole percent) with grain size (130 ${\mu}m$) and level of impurities (Cu, Fe and Ni) less than (0.02%).

• KIEAE Journal
• /
• v.16 no.4
• /
• pp.79-86
• /
• 2016

Purpose: Frequently, the apartment management offices have difficulties in effective repair works due to their insufficient technological capability to operate long-term repair program. There also have been many cases of failure in executing urgent repairs mainly because the repair allowance has not accumulated enough for the repair works on time. This study aimed to determine core items in apartment maintenance in order to reduce the confusion and unnecessary efforts for the management office by suggesting simple list of repair items. Method: Core items are defined using several indicators. The degrees of necessity for repair work(NRW) are calculated combining the impacts to living, safety, and aesthetics. Then the degrees of burden of repair cost(BRC) are estimated by analyzing actual long-term repair program of three apartment complexes. Lastly the degrees of accumulation demand for repair allowance(AD) are calculated with NRW and BRC. Result: The core items and essential items are suggested for three apartment types as case studies based on the indicators of NRW, BRC, and AD. Then, the required accumulated allowance per $m^2$ was calculated to effectively implement repair works.

• Korean Journal of Materials Research
• /
• v.28 no.12
• /
• pp.748-757
• /
• 2018

Inorganic semiconductor compounds, e.g., CIGS and CZTS, are promising materials for thin film solar cells because of their high light absorption coefficient and stability. Research on thin film solar cells using this compound has made remarkable progress in the last two decades. Vacuum-based processes, e.g., co-evaporation and sputtering, are well established to obtain high-efficiency CIGS and/or CZTS thin film solar cells with over 20 % of power conversion. However, because the vacuum-based processes need high cost equipment, they pose technological barriers to producing low-cost and large area photovoltaic cells. Recently, non-vacuum based processes, for example the solution/nanoparticle precursor process, the electrodeposition method, or the polymer-capped precursors process, have been intensively studied to reduce capital expenditure. Lately, over 17 % of energy conversion efficiency has been reported by solution precursors methods in CIGS solar cells. This article reviews the status of non-vacuum techniques that are used to fabricate CIGS and CZTS thin films solar cells.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.24 no.4
• /
• pp.48-54
• /
• 2020

Low cost launch vehicle for next-generation is underway in advanced space countries such as the United States, Europe, Japan and China. This paper surveys the latest technological trends in avionics system, including ground management system. In the case of on-board equipment, to make short the development period and reduce the cost, the equipment is standardized and modularized for each functions to flexibly respond to changes in system requirements. In addition, a network is applied to all inter-equipment interfaces and a powerful self-diagnostic function is included in the equipment to realize automation/simplification of the interface with the ground system, and it is confirmed that an efficient launcher system is realized.

• Membrane and Water Treatment
• /
• v.13 no.3
• /
• pp.147-166
• /
• 2022

Liquid-liquid membrane contactor (LLMC), a device that exchanges dissolved gas molecules between the two sides of a hydrophobic membrane through membrane pores, can be employed to extract ammoniacal nitrogen from a feed solution, which is transported across the membrane and accumulated in a stripping solution. This LLMC process offers the promise of improving the sustainability of the global nitrogen cycle by cost-effectively recovering ammonia from wastewater. Despite recent technological advances in LLMC processes, a comprehensive review of their feasibility for ammonia recovery is rarely found in the literature. Our paper aims to close this knowledge gap, and in addition to analyze the challenges and provide potential solutions for improvement. We begin with discussions on the operational principles of the LLMC process for ammonia recovery and membrane types and membrane configurations commonly used in the process. We then assess the performance of the process by reviewing publications that demonstrate its practical application. Challenges involved in the implementation of the LLMC process, such as membrane fouling, membrane wetting, and chemical requirements, are presented, along with discussions on potential strategies to address each. These strategies, including membrane modification, hybrid process design, and process optimization based on cost-benefit analysis, guide the reader to identify key areas of future research and development.

• Journal of Korean Port Research
• /
• v.6 no.1
• /
• pp.49-68
• /
• 1992

Recently changes in the technological environment of marine transportation and the increase of traffic volume have fostered a revolution in the design and operation of port and also playing a major role in the development of new types of port in Asian. These changes are dynamic and will continue to influence port physical distribution system. The port of Pusan has been hardly able to handle the traffic increases in recent years by expansion increased mechanization and other operational and institutional improvements but, further traffic increases bring about critical congestion and such congestion is an economic cost to the country in terms of cost of physical distribution. This paper treats the development of entirely new port of Pusan and related transportation system by considering the existing or expected need for improved port capacity and services. The western part of GADUK island is selected as the optimum port site through the detailed analysis of the physical requirement and careful consideration of regional development and since the lead time of the national development plan including the port project from initial planning to implementation is considered as long as 7 to 10 years the aggregated master plan for port development is made and implemented in the year of 2012.

• Management & Information Systems Review
• /
• v.28 no.4
• /
• pp.109-129
• /
• 2009

This study aims at investigating the effectiveness of SME's R&D system empirically. Specifically, this study analyze the relationships among R&D inputs(R&D investment, R&D human resource management), process(R&D planning, external network, internal cooperation), and output(technological innovation). A questionnaire was developed to measure the above variables. To test these relations, data were collected from the small and medium-sized IT firms located in Daegu-Kyungbuk region. The survey data of 154 firms were integrated as the empirical base for testing the relations. Most respondents were from the managers. Structural equation modeling analyses were used to examine the relations. Major results are as follows: Firstly, R&D HRM was positively and significantly influenced on the R&D planning. Secondly, R&D planning was positively and significantly affected on the external network, internal cooperation, and technological innovation. Thirdly, the both relations between R&D investment and R&D planning, and external network and technological innovation were not significant statistically. These results suggest the following implications. First, R&D human resource management is very important for IT SMEs. Secondly, internal cooperation mediates R&D inputs and technological innovation by approaching the other department's unique resources and by sharing the cost of new resource development. Several future researches need to overcome the limitations of this research. First, this study's sample was based on the small and medium-sized IT firms just located in Daegu-Kyungbuk region. This limitation may imply that empirical results can not represent overall small and medium-sized firm's situations. Therefore, future research needs to include different samples. Secondly, this study depends on the latitudinal study.

• 한국벤처창업학회:학술대회논문집
• /
• 2008.04a
• /
• pp.33-59
• /
• 2008

Since the late 20th century, due to the globalization of markets and the rapid developments of information and communication technologies, the world has entered into the age of fierce competition. With their abundant low-cost labor, former communist countries such as China, Russia and East Europe and low-developed countries such as India and Brazil have received investments from major industrial companies. There are no other alternatives for Korea and OECD countries to move the industrial economy to the knowledge based innovation system. In knowledge based innovation system, economic development and employment of a region and nation depend solely on the number of its companies and their competitiveness. In this research, after reviewing the current state of technological innovation small companies in korea, we provide a theoretical framework to promote the level of technological innovative entrepreneurship. The framework is based on a value system model that consist of supply factors, demand factors, and supporting institutions. In order to create more innovative small businesses, we insist on the followings. First, more R&D activities related with promising new technologies should be performed. Second, more R&D funds for technological innovation small companies should be provided from governments. Third, more M&A transactions and technology transactions should be marketed freely and competitively. Fourth, more business incubating services and venture capital services should be provided. Fifth, entrepreneurship and innovation culture should be popular and institutionized among people.

• Journal of Communications and Networks
• /
• v.5 no.4
• /
• pp.386-393
• /
• 2003

Future wireless networks are expected to achieve high bit rates at low cost, enabling multimedia and QoS-based services over the wireless medium. The impulse radio ultra-wide band (IR-UWB) technique is a promising candidate in the deployment of such networks, thanks to its potential robustness and capacity. In the past, most of the UWB research focused on hardware and physical layer aspects in order to solve the technological challenges posed by IR-UWB. UWB peculiar characteristics may, however, also stimulate innovative higher layers’ design. This work addresses MAC issues for UWB communication systems. Key areas such as medium sharing, MAC organization, packet scheduling and power control are reviewed. The impact of UWB on the above functions is discussed, and areas which require UWB specific design are identified. Finally, novel MAC functions enabled by UWB specific features, i.e., precise ranging and positioning, are presented.

• The Korean Journal of Pain
• /
• v.25 no.3
• /
• pp.143-150
• /
• 2012

Spinal cord stimulation has become a widely used and efficient alternative for the management of refractory chronic pain that is unresponsive to conservative therapies. Technological improvements have been considerable and the current neuromodulation devices are both extremely sophisticated and reliable in obtaining good results for various clinical situations of chronic pain, such as failed back surgery syndrome, complex regional pain syndrome, ischemic and coronary artery disease. This technique is likely to possess a savings in costs compared with alternative therapy strategies despite its high initial cost. Spinal cord stimulation continues to be a valuable tool in the treatment of chronic disabling pain.