• Journal of Korea Multimedia Society
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• v.13 no.3
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• pp.438-456
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• 2010

Iris recognition uses a unique iris pattern of user to identify person. In order to enhance the performance of iris recognition, it is reported that the diameter of iris region should be greater than 200 pixels in the captured iris image. So, the previous iris system used zoom lens camera, which can increase the size and cost of system. To overcome these problems, we propose a new method of enhancing the accuracy of iris recognition on low-resolution iris images which are captured without a zoom lens. This research is novel in the following two ways compared to previous works. First, this research is the first one to analyze the performance degradation of iris recognition according to the decrease of the image resolution by excluding other factors such as image blurring and the occlusion of eyelid and eyelash. Second, in order to restore a high-resolution iris image from single low-resolution one, we propose a new method based on multiple multi-layered perceptrons (MLPs) which are trained according to the edge direction of iris patterns. From that, the accuracy of iris recognition with the restored images was much enhanced. Experimental results showed that when the iris images down-sampled by 6% compared to the original image were restored into the high resolution ones by using the proposed method, the EER of iris recognition was reduced as much as 0.133% (1.485% - 1.352%) in comparison with that by using bi-linear interpolation

• Journal of Navigation and Port Research
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• v.31 no.5 s.121
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• pp.325-332
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• 2007

This study develops a control algorithm on berthing/unberthing system using a joystick for ships with thrusters and a rudder. A nonlinear mathematical model for low speed maneuvering of typical container ships is used to develop a MIMO(multi-input multi-output) nonlinear control algorithm for velocity feedback joystick control. Also a virtual HILS(hardware in the loop simulation) software program for berthing/unberthing is developed to test the performance of the nonlinear and a PID control algorithm. The program is developed using LabWindow/CVI, and a user can see current position and desired trajectory of ship in a monitor, then he can control forward and yaw velocities of a ship using a joystick. The simulation results show that the nonlinear mfd the PID controller have superior performance over a simple open loop joystick control algorithm.

• Journal of Navigation and Port Research
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• v.38 no.3
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• pp.227-232
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• 2014

There are three essential components of eLoran: dLoran, data map of ASF, and the Loran data channel. Particularly, dLoran improves navigation accuracy, which is the core technology of eLoran systems. The requirement of HEA's absolute accuracy, less than 20 meters, can be satisfied via dLoran measurements and their corrections. In this study, dLoran measurements using the Pohang Loran-C (9930M) station signal were conducted at Yeongil Bay. We established a dLoran reference station at Homigot Management Office for navigation aids within the Bay. We estimated the effectiveness of the dLoran between the reference site (Homigot Management Office) and a test site (Heunghwan beach) by measuring TOAs. We verified that the TOA data measured at these two regions were highly correlated. The temporal differences in the data between the dLoran reference station and test site were about 10~30 ns per day, which is equivalent to a ranging error of 3~9 m. This result shows that eLoran can meet the requirement of 8~20 meters position accuracy for maritime HEA by correcting the ASF at the user's receiver.

• Progress in Medical Physics
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• v.28 no.1
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• pp.1-10
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• 2017

The difference between three-dimensional (3D) and four-dimensional (4D) dose could be affected by factors such as tumor size and motion. To quantitatively analyze the effects of these factors, a phantom that can independently control each factor is required. The purpose of this study is to develop a deformable lung phantom with the above attributes and evaluate the characteristics. A phantom was designed to simulate diaphragm motion with amplitude in the range 1~7 cm and period up to ${\geq}2s$ of regular breathing. To simulate different tumors sizes, custom molds were created using a 3D printer and filled with liquid silicone. The accuracy of the phantom diaphragm motion was assessed by comparing measured motion with predicted motion. Because the phantom diaphragm motion is not identical to the tumor motion, the correlation between the diaphragm and tumor motions was calculated by a curve fitting method to emulate user-intended tumor motion. Tumors of different sizes were located at same position, and tumor set-up positions were evaluated. The accuracy of phantom diaphragm motion was better than 1 mm. The diaphragm-tumor correlation showed that the tumor motion in the superior-inferior direction increased with increasing diaphragm motion. The tumor motion was larger in the $10cm^3$ tumor than in the $90cm^3$ tumor. The range of difference between the tumor set-up positions was 0 to 0.45 cm. This phantom showed independently adjusting factors such as tumor size and motion to facilitate quantitative analysis of the dosimetric impact of respiratory motion according to these factors.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.2
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• pp.372-377
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• 2016

Communication flow is changing rapidly. Recently, a range of wearable devices such as wearable glasses and wearable watch, have been launched. These kinds of wearable devices help people to live a more comfortable life. Wearable devices most have an antenna for wireless communication. This paper reports a transparent antenna that is made of an optically transparent material for wearable glasses. Transparent antenna can be applied to smart windows and will not disturb the view of user. IZTO/Ag/IZTO multilayer electrode has higher electrical and optical properties. This antenna is available because of its good electrical properties. This study measured the performance of the proposed transparent antenna, which is made of a multilayer electrode, applied to a lens. The proposed antenna was simulated with several substrates. The antenna impedance was matched with length and width of the antenna. The antenna's conductivity and transparency was measured using a HMS-3000 and UV-spectrometer. A 40nm thick Ag single layer antenna was fabricated on a flexible polyimide substrate for comparing the antenna performances. The fabricated antenna is useable at a frequency of 2.4-2.5GHz, which is suitable for Wifi communications and has peak gain of 2.89dBi and an efficiency of 34%.

• The KIPS Transactions:PartB
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• v.10B no.6
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• pp.599-610
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• 2003

The Web plays an important role as information source and most Web applications are document-centric. A document implies an intention of its own designer, which can be utilized actively in automation of business processes. Through an understanding of an intrinsic nature of a document function, we can see a document as an executable computer program in a special case. For this approach, we propose an active document model that is composed of form, knowledge base, rules, and queries. For reusability and interoperability of a document, each component of the proposed model is uniformly represented in XML. The proposed active document not only plays a passive role in providing user interfaces, but also is a document that a machine can infer and process with reading a procedure of document processing and business rules intended by document designers. Through this approach, document can interact with machines and can cooperate with other applications. For applicability of our active document, we show a case study for the processing of purchase orders in a B2B e-Commerce system. This paper is expected to provide the framework of accelerating the development of intelligent applications through our approach regards form document as a computer program. In short, the proposed active document contains knowledge representation and processing method, consequently our document will play an important role in providing a concept of document of pursuing in Semantic Web.

• The KIPS Transactions:PartD
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• v.17D no.5
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• pp.371-382
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• 2010

One of the advantages of the mobile internet is that it is accessible everywhere. However, producing the mobile internet contents is hard because the standards of the contents are different depending on the telecommunications companies and the mobile phone terminals. Because of this, mobile contents production has not been activated and profit models are rarely found. In order to vitalize the mobile contents, we developed the Mobile UCC (User Created Contents) Phone Page Service with which general users can produce and provide the mobile phone pages easily. In addition, we began to provide advertisement on the UCC phone pages as a profit model. However, as mentioned already, the contents that meet each of the standards should be prepared in advance to be compatible with the different standards. For this reason, only one advertisement could be provided on one UCC phone page. Previous studies were focused on the standardization of different standards by integrating them. Though the standardization may be applicable to the mobile phones that will be newly released, it is hardly applied to the conventional mobile phones. To solve the abovementioned problems and improve the drawbacks of the conventional studies, we proposed in this article the technology to synthesize the phone page contents and independent advertisement at the moment when the UCC phone page prepared by the users is provided in real time. This technology allows to provide various advertisement on one UCC phone page and administrate the start, end and frequency of specific advertisements. This method was applied in this study to vitalize the mobile contents and improve the profit model.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.1
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• pp.7-14
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• 2013

Presently, there are many different technologies used for position detection. However, as signal-receiving devices operating in different locations must detect the precise position of objects located at long distances, it is essential to know the precise time at which an object's or a user's terminal device sends a signal. For this purpose, the existing time of arrival (ToA) technology is not sufficiently reliable, and the existing time difference of arrival (TDoA) technology is more suitable. If a TDoA-based electric surveillance system and other tracking devices fail to achieve precise time-synchronization between devices with separation distance operation, it is impossible to obtain correct TDoA values from the signals sent by the signal-receiving devices; this failure to obtain the correct values directly affects the location estimation error. For this reason, the technology for achieving precise time synchronization between signal-receiving devices in separation distance operation, among the technologies previously mentioned, is a core technology for detecting TDoA-based locations. In this paper, the accuracy of the proposed time synchronization and the measurement error in the TDoA-based location detection technology is evaluated. The TDoA-based location measurement error is significantly improved when using the proposed method for time-synchronization error reduction.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.8A
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• pp.648-660
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• 2012

The low-power, low-cost femtocell network has been proposed not only to alleviate traffic load to the macro base station (eNB) but also to cover the indoor coverage hole problem. However, in the dense femtocell environment where many femtocells are deployed to cover the whole large office building, performance of such femtocell environment can be deteriorated due to severe co-channel interference problem between the eNB and femtocells and among neighboring femtocells. In particular, a macro UE(mUE) located within femtocell coverage may experience severe co-channel interference from surrounding femtocells. Therefore, In this paper, we propose a novel power control schemes to mitigate interference to a mUE under such dense LTE femtocell environment. With proposed femtocell power control schemes, performance of the mUE can be greatly improved in terms of the outage probability and the SINR while maintaining satisfying femtocell performance. Simulation based performance study shows that the proposed power control scheme is able to enhance mUE performance more than 30% than the conventional dense femtocell in terms of the two performance metrics.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.6
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• pp.2604-2611
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• 2013

The Personal Rapid Transit(PRT) system has been highly interested in future transportation developments due to its on-demand and optimized door-to-door transport capability. However, the major impediments to the commercialization of PRT are the high cost for construction of infrastructures as opposed to the small transport capacity and difficulty in defining the role of PRT in building a balanced transportation system. In this study, the vertical transfer device for the PRT vehicle is developed to provide more flexible and better compatible urban mobility services between means of transportation, which is expected to meet particular demands in a particular environment. This apparatus was initially designed based on the basis of vertical circulating conveyors with steel chains, which is frequently used in logistics. Its advantages are capable of the non-stop loading and reduced head-way time. Most importantly, it was intensified by the additional idea to ensure the stable and reliable transfer of the PRT vehicle fully loaded with passengers. The 1/10-scale prototype was successfully tested to demonstrate a fundamental mechanism of vertical transfer and identify unexpected user requirements prior to a real manufacturing process.