• Journal of the Korean Society for Marine Environment & Energy
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• v.16 no.1
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• pp.1-8
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• 2013

This study focuses on a ship detection and tracking method using Frequency Modulated Continuous Wave (FMCW) radar used for horizontal surveillance. In general, FMCW radar can play an important role in maritime surveillance, because it has many advantages such as low warm-up time, low power consumption, and its all weather performance. In this paper, we introduce an effective method for data and signal processing of ship's detecting and tracking using the X-band radar. Ships information was extracted using an image-based processing method such as the land masking and morphological filtering with a threshold for a cycle data merged from raw data (spoke data). After that, ships was tracked using search-window that is ship's expected rectangle area in the next frame considering expected maximum speed (19 kts) and interval time (5 sec). By using this method, the tracking results for most of the moving object tracking was successful and those results were compared with AIS (Automatic Identification System) for ships position. Therefore, it can be said that the practical application of this detection and tracking method using FMCW radar improve the maritime safety as well as expand the surveillance coverage cost-effectively. Algorithm improvements are required for an enhancement of small ship detection and tracking technique in the future.

• Journal of the Korean Geosynthetics Society
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• v.11 no.4
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• pp.27-35
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• 2012

Facings of mechanically stabilized earth retaining walls have function to fix the reinforcement and prevent backfill loss, but the walls are lack of structural rigidity capable of resisting applied loads. The reinforced subgrade with rigid wall was developed to have the structural functions under train loading. Though it has lots of advantages such as small deformation after construction, its negative side effects of economics and difficult construction were mainly mentioned and not practically used. To apply it for railroad subgrade, this study focus on the construction cost down and the enhancement of constructability without functional loss. To do so, the behaviors of reinforced subgrade with rigid wall were evaluated with the change of the vertical spacing and length of reinforcement. Small scale model tests (1/10 scale) and 3 m full scale tests were performed to evaluate deformation characteristics of reinforced subgrade under simulated train loading. Even though it uses short reinforcement, it showed small horizontal displacement of wall and plastic settlement of subgrade. Also, it was verified that not only 30 cm but also 40 cm of vertical spacing of reinforcement had good performance in serviceability aspects.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.6
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• pp.475-482
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• 2014

This paper presents the results of an experimental feasibility study on low-temperature differential Stirling engines with water spray heat transfer. The water spray enhances the efficiency of the heat transfer from heat sources to the engine and reduces the performance degeneration due to the dead volumes of conventional heat exchangers. A test Stirling engine was developed and an experiment was conducted to determine the characteristics for the initial start-up, steady-state operation, and power output for various flow rates and temperatures of hot supply water. The test results showed that larger flow rates led to reductions in the minimum working temperature of the hot water at start-up. During a series of steady-state operations, higher flow rates and temperatures increased the working speed. Furthermore, the work per cycle and power output were also increased. Eventually, the test Stirling engine had a power level of 0.05 W. Based on this, further research will be conducted to obtain a higher power output and investigate various applications.

• International Commerce and Information Review
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• v.16 no.4
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• pp.333-362
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• 2014

This study uncovered some issues that have constrained the development of logistics performance in Cambodia. Firstly, literature review was narrowed down to include studies involving the relationship between Logistics and transportation, the relationship between the infrastructure and economic growth and the important role of logistics on economic growth and poverty reduction. Then the next step the study identified some issues related to transport infrastructure that were assumed to cause the enhancement of logistics sector. Moreover, a case study about cost and time analysis was used to address some issues of logistics cost in Cambodia comparing to its neighboring countries: Thailand and Vietnam. Based on the time and cost analysis, it revealed that the logistics cost in Cambodia is much high than Thailand and Vietnam. In addition, some logistics issues were found through other two case studies about the export and trade facilitation. The participants raised some issues related to issuance of certificate of origin, the availability of information about agreements, laws, rules, and regulations, checkpoints along the corridor and opening hours of logistics service providers and slow processes. Then the authors suggested some appropriate solutions to answer to the current issues related to transport infrastructure and logistics sector in Cambodia.

• Journal of Korean Academy of Nursing
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• v.29 no.2
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• pp.314-327
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• 1999

In this study, domains, contents, and effects of pre-existed intervention programs for individuals with arthritis were meta-analyzed to develop arthritis health promotion program based on Holistic Model. The developed program includes strategies of cognition, environment, and behavior. and also generates positive changes in the physical, psychological, and social demensions. Then needs assessment on conveniently selected 153 women who visited a university hospital in Seoul or in Inchon are conducted to identify the objective domains of arthritis health promotion program According to the study results. target health problems of the arthritis health promotion program were shown as pain, disability, depression, and role impediment in social domain. These objectives could be achieved by including the strategies of changing cognition, the strategies of changing behavior through learning the skill related to the health promoting behavior. and the strategies of changing environment in the health promotion program. That is, it is analyzed that the contents of program are not exclusive one another in physical. psychological. and social demensions, and also are not exclusive one another in aspect of cognition, behavior, and environment. The necessary methods to achieve the desired objectives for the developed arthritis health promotion program and evaluation subjects are as follows : (1) In the arthritis health promotion program, knowledge on management of arthritis, efficacy related to arthritis management, skill for pain management, skill for exercise, establishment of positive self-concept, enhancement of positive thinking, stress management. skill for problem solving, skill for setting goals. skill for requesting help, and skill for communication are all included. Through the improvement of all those strategies, intermediate objectives, such as “joint protection, and maintenance of pain management behavior”, “maintenance of regular exercise”, and “promotion of coping skill in psychosocial dimension” are achieved. (2) These intermediate objectives are also the methods for achieving objectives in next stage. It implies that through the intermediate objectives. the final objectives such as “minimization of physical symptoms and signs”, “maximization of psychological function”, and “maximazation of role performance in social domain” could be achieved. Each of these final objectives reflects the different dimension of quality of life, respectively. When these objectives are achieved, the quality of life that client perceives is improved. Therefore, through evaluation of these final objectives, the level of achieving final outcome of arthritis health promotion such as quality of life is determined.

• Bulletin of the Korean Chemical Society
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• v.35 no.5
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• pp.1516-1522
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• 2014

A series of 20 wt % $(NH_4)_2SO_4$ and 3 wt % $Al_2O_3$ surface treatments were applied to $Li[Li_{0.2}Mn_{0.54}Co_{0.13}Ni_{0.13}]O_2$ substrates. The $Li[Li_{0.2}Mn_{0.54}Co_{0.13}Ni_{0.13}]O_2$ substrates were synthesized using a co-precipitation method. Sample (a) was left pristine and variations of the 20 wt % $(NH_4)_2SO_4$ and 3 wt % $Al_2O_3$ were applied to samples (b), (c) and (d). XRD was used to verify the space group of the samples as R$\bar{3}$m. Additional morphology and particle size data were obtained using SEM imagery. The $Al_2O_3$ coating layers of sample (b) and (d) were confirmed by TEM images and EDS mapping of the SEM images. 2032-type coin cells were fabricated in a glove box in order to investigate their electrochemical properties. The cells were charged and discharged at room temperature ($25^{\circ}C$) between 2.0V and 4.8V during the first cycle. The cells were then charged and discharged between 2.0V and 4.6V in subsequent cycles. Sample (d) exhibited lower irreversible capacity loss (ICL) in the first charge-discharge cycle as compared to sample (c). Sample (d) also had a higher discharge capacity of ~250 mAh/g during the first and second charge-discharge cycles when compared with sample (c). The rate capability of the $Al_2O_3$-coated sample (b) and (d) was lower when compared with sample (a) and (c). Sample (d), coated with $Al_2O_3$ after the surface treatment with $(NH_4)_2SO_4$, showed an improvement in cycle performance as well as an enhancement of discharge capacity. The thermal stability of sample (d) was higher than that of the sample (c) as the result of DSC.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.6
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• pp.11-18
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• 2009

In this paper, a hierarchical link allocation algorithm between mobile stations (MSs) and the corresponding base station (BS) by an optimal utilization of relay stations (RSs) is proposed to improve throughput of RS systems. In the proposed hierarchical algorithm, each RS operates cognitive radio functions to sense the degree of satisfaction in the quality of services (QoSs) and then selects the candidate set of MSs to have links with the RS. Such information is reported to the BS, where an auction process is performed to get an optimal allocation of communication links between the MSs and the BS. To maximize system throughput, the proposed auction algorithm is conducted upon bidding prices of communication links, considering both the co-channel interference (CCI) information shared among adjacent cells and the QoS enhancement information for each MS collected from RSs. The BS then switches the communication links of the auction winner MSs through the corresponding RS. The computer simulation shows that the proposed algorithm enhances the user QoS more than the conventional algorithm, especially for RS systems with more users requiring higher QoS. The proposed algorithm has also been proved to have more robust performance than the conventional one when the traffic load is higher and the CCI becomes stronger.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.11
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• pp.15-19
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• 2007

This paper reports the effects of Ar ion beam surface treatment on a $SiO_2$ dielectric layer in organic thin film transistors. We compared the electrical properties of pentacene-based OTFTs, treated by $O_2$ plasma or Ar ion beam treatments and characterized the states of the surface of the dielectric by using atomic force microscopy and X-ray photoelectron spectroscopy. For the sample which received $O_2$ plasma treatment, the mobility increased significantly but the on/off current ratio was found very low. The Ar ion beam-treated sample showed a very high on/off current ratio as well as a moderately improved mobility. XPS data taken from the dielectric surfaces after each of treatments exhibit that the ratio of between Si-O bonds and O-Si-O bonds was much higher in the $O_2$ plasma treated surface than in the Ar ion beam treated surface. We believe that our surface treatment using an inert gas, Ar, carried out an effective surface cleaning while keeping surface damage very low, and also the improved device performances was achieved as a consequence of improved surface condition.

• The Journal of the Korea Contents Association
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• v.9 no.12
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• pp.528-536
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• 2009

Recently, the importance of IPTV providing multimedia service over IP based networks managed to provide the required level of quality of service and experience, security, interactivity and reliability has been gradually increasing by the commercialization of its service. However, the original purposes of IPTV service - contents are produced and consumed anytime, anywhere, and over any device at the same time - have not been satisfied by service providers because most services offered by service providers depend on closed IPTV platform. In this paper, we propose an open IPTV service platform that an individual or small company can easily produce contents and offer IPTV service independently from the existing closed IPTV platform.. The proposed IPTV platform exploits overlay multicast scheme to offer reasonable service under the environment where network bandwidth and processor resource are limited. It also uses CDN-like scheme to ensure the quality of transmitted contents. The performance evaluation shows that the proposed IPTV platform has the possibility of being an open IPTV platform considering its results such as the quality of transmitted contents, the transmission rate, the channel zapping time, and so on. It also shows that proposed IPTV platform could be applied to real IPTV service with continuous enhancement of its functions and user interfaces.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.441-441
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• 2009

Dye-sensitized solar cells (DSSCs) have been widely investigated as a next-generation solar cell because of their simple fabrication process and low coats. The cells use a porous nanocrystalline TiO2 matrix coated with a sensitizer dye that acts as the light-harvesting element. The photo-exited dye injects electrons into the $TiO_2$ particles, and the oxide dye reacts with I- in the electrolyte in regenerative cycle that is completed by the reduction of $I_3^-$ at a platinum-coated counter electrode. Since $TiO_2$ porous film plays a key role in the enhancement of photoelectric conversion efficiency of DSSC, many scientists focus their researches on it. Especially, a high light-to-electricity conversion efficiency results from particle size and crystallographic phase, film porosity, surface structure, charge and surface area to volume ratio of porous $TiO_2$ electrodes, on which the dye can be sufficiently adsorbed. Effective treatment of the photoanode is important to improve DSSC performance. In this paper, to obtain properties of surface and dispersion as nitric acid treated $TiO_2$ photoelectrode was investigate. The photovoltaic characteristics of DSSCs based the electrode fabricated by nitric acid pre-treatment $TiO_2$ materials gave better performances on both of short circuit current density and open circuit voltage. We compare dispersion of $TiO_2$ nanoparticles before and after nitric acid treatment and measured Ti oxidized state from XPS. Low charge transfer resistance was obtained in nitric acid treated sample than that of untreated sample. The dye-sensitized solar cell based on the nitric acid treatment had open-circuit voltage of 0.71 V, a short-circuit current of 15.2 mAcm-2 and an energy conversion efficiency of 6.6 % under light intensity of $100\;mWcm^{-2}$. About 14 % increases in efficiency obtained when the $TiO_2$ electrode was treated by nitric acid.